基础篇

//查询时间，友好提示

$sql = "select date_format(create_time, '%Y-%m-%d') as day from table_name";

//int 时间戳类型

$sql = "select from_unixtime(create_time, '%Y-%m-%d') as day from table_name";

//一个sql返回多个总数

$sql = "select count(*) all, " ;

$sql .= " count(case when status = 1 then status end) status_1_num, ";

$sql .= " count(case when status = 2 then status end) status_2_num ";

$sql .= " from table_name";

//Update Join / Delete Join

$sql = "update table_name_1 ";

$sql .= " inner join table_name_2 on table_name_1.id = table_name_2.uid ";

$sql .= " inner join table_name_3 on table_name_3.id = table_name_1.tid ";

$sql .= " set *** = *** ";

$sql .= " where *** ";

//delete join 同上。

//替换某字段的内容的语句

$sql = "update table_name set content = REPLACE(content, 'aaa', 'bbb') ";

$sql .= " where (content like '%aaa%')";

//获取表中某字段包含某字符串的数据

$sql = "SELECT * FROM `表名` WHERE LOCATE('关键字', 字段名) ";

//获取字段中的前4位

$sql = "SELECT SUBSTRING(字段名,1,4) FROM 表名 ";

//查找表中多余的重复记录

//单个字段

$sql = "select * from 表名 where 字段名 in ";

$sql .= "(select 字段名 from 表名 group by 字段名 having count(字段名) > 1 )";

//多个字段

$sql = "select * from 表名 别名 where (别名.字段1,别名.字段2) in ";

$sql .= "(select 字段1,字段2 from 表名 group by 字段1,字段2 having count(*) > 1 )";

//删除表中多余的重复记录(留id最小)

//单个字段

$sql = "delete from 表名 where 字段名 in ";

$sql .= "(select 字段名 from 表名 group by 字段名 having count(字段名) > 1)  ";

$sql .= "and 主键ID not in ";

$sql .= "(select min(主键ID) from 表名 group by 字段名 having count(字段名 )>1) ";

//多个字段

$sql = "delete from 表名 别名 where (别名.字段1,别名.字段2) in ";

$sql .= "(select 字段1,字段2 from 表名 group by 字段1,字段2 having count(*) > 1) ";

$sql .= "and 主键ID not in ";

$sql .= "(select min(主键ID) from 表名 group by 字段1,字段2 having count(*)>1) ";

业务篇

连续范围问题

//创建测试表

CREATE TABLE `test_number` (

`id` int(10) unsigned NOT NULL AUTO_INCREMENT,

`number` int(11) unsigned NOT NULL DEFAULT '0' COMMENT '数字',

PRIMARY KEY (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8

//创建测试数据

insert into test_number values(1,1);

insert into test_number values(2,2);

insert into test_number values(3,3);

insert into test_number values(4,5);

insert into test_number values(5,7);

insert into test_number values(6,8);

insert into test_number values(7,10);

insert into test_number values(8,11);

实验目标：求数字的连续范围。

根据上面的数据，应该得到的范围。

1-3

5-5

7-8

10-11

//执行Sql

select min(number) start_range,max(number) end_range

from

(

select number,rn,number-rn diff from

(

select number,@number:=@number+1 rn from test_number,(select @number:=0) as number

) b

) c group by diff;

签到问题

//创建参考表(模拟数据需要用到)

CREATE TABLE `test_nums` (

`id` int(11) unsigned NOT NULL AUTO_INCREMENT,

PRIMARY KEY (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='参考表';

//模拟数据，插入 1-10000 连续数据.

//创建测试表

CREATE TABLE `test_sign_history` (

`id` int(10) unsigned NOT NULL AUTO_INCREMENT,

`uid` int(11) unsigned NOT NULL DEFAULT '0' COMMENT '用户ID',

`create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '签到时间',

PRIMARY KEY (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='签到历史表';

//创建测试数据

insert into test_sign_history(uid,create_time)

select ceil(rand()*10000),str_to_date('2016-12-11','%Y-%m-%d')+interval ceil(rand()*10000) minute

from test_nums where id<31;

//统计每天的每小时用户签到情况

select

h,

sum(case when create_time='2016-12-11' then c else 0 end) 11Sign,

sum(case when create_time='2016-12-12' then c else 0 end) 12Sign,

sum(case when create_time='2016-12-13' then c else 0 end) 13Sign,

sum(case when create_time='2016-12-14' then c else 0 end) 14Sign,

sum(case when create_time='2016-12-15' then c else 0 end) 15Sign,

sum(case when create_time='2016-12-16' then c else 0 end) 16Sign,

sum(case when create_time='2016-12-17' then c else 0 end) 17Sign

from

(

select

date_format(create_time,'%Y-%m-%d') create_time,

hour(create_time) h,

count(*) c

from test_sign_history

group by

date_format(create_time,'%Y-%m-%d'),

hour(create_time)

) a

group by h with rollup;

//统计每天的每小时用户签到情况(当某个小时没有数据时，显示0)

select

h ,

sum(case when create_time='2016-12-11' then c else 0 end) 11Sign,

sum(case when create_time='2016-12-12' then c else 0 end) 12Sign,

sum(case when create_time='2016-12-13' then c else 0 end) 13Sign,

sum(case when create_time='2016-12-14' then c else 0 end) 14Sign,

sum(case when create_time='2016-12-15' then c else 0 end) 15Sign,

sum(case when create_time='2016-12-16' then c else 0 end) 16Sign,

sum(case when create_time='2016-12-17' then c else 0 end) 17Sign

from

(

select b.h h,c.create_time,c.c from

(

select id-1 h from test_nums where id<=24

) b

left join

(

select

date_format(create_time,'%Y-%m-%d') create_time,

hour(create_time) h,

count(*) c

from test_sign_history

group by

date_format(create_time,'%Y-%m-%d'),

hour(create_time)

) c on (b.h=c.h)

) a

group by h with rollup;

//统计每天的用户签到数据和每天的增量数据

select

type,

sum(case when create_time='2016-12-11' then c else 0 end) 11Sign,

sum(case when create_time='2016-12-12' then c else 0 end) 12Sign,

sum(case when create_time='2016-12-13' then c else 0 end) 13Sign,

sum(case when create_time='2016-12-14' then c else 0 end) 14Sign,

sum(case when create_time='2016-12-15' then c else 0 end) 15Sign,

sum(case when create_time='2016-12-16' then c else 0 end) 16Sign,

sum(case when create_time='2016-12-17' then c else 0 end) 17Sign

from

(

select b.create_time,ifnull(b.c-c.c,0) c,'Increment' type from

(

select

date_format(create_time,'%Y-%m-%d') create_time,

count(*) c

from test_sign_history

group by

date_format(create_time,'%Y-%m-%d')

) b

left join

(

select

date_format(create_time,'%Y-%m-%d') create_time,

count(*) c

from test_sign_history

group by

date_format(create_time,'%Y-%m-%d')

) c on(b.create_time=c.create_time+ interval 1 day)

union all

select

date_format(create_time,'%Y-%m-%d') create_time,

count(*) c,

'Current'

from test_sign_history

group by

date_format(create_time,'%Y-%m-%d')

) a

group by type

order by case when type='Current' then 1 else 0 end desc;

//模拟不同的用户签到了不同的天数

insert into test_sign_history(uid,create_time)

select uid,create_time + interval ceil(rand()*10) day from test_sign_history,test_nums

where test_nums.id <10 order by rand() limit 150;

//统计签到天数相同的用户数量

select

sum(case when day=1 then cn else 0 end) 1Day,

sum(case when day=2 then cn else 0 end) 2Day,

sum(case when day=3 then cn else 0 end) 3Day,

sum(case when day=4 then cn else 0 end) 4Day,

sum(case when day=5 then cn else 0 end) 5Day,

sum(case when day=6 then cn else 0 end) 6Day,

sum(case when day=7 then cn else 0 end) 7Day,

sum(case when day=8 then cn else 0 end) 8Day,

sum(case when day=9 then cn else 0 end) 9Day,

sum(case when day=10 then cn else 0 end) 10Day

from

(

select c day,count(*) cn

from

(

select uid,count(*) c from test_sign_history group by uid

) a

group by c

) b;

//统计每个用户的连续签到时间

select * from (

select d.*,

@ggid := @cggid,

@cggid := d.uid,

if(@ggid = @cggid, @grank := @grank + 1, @grank := 1) grank

from

(

select uid,min(c.create_time) begin_date ,max(c.create_time) end_date,count(*) count from

(

select

b.*,

@gid := @cgid,

@cgid := b.uid,

if(@gid = @cgid, @rank := @rank + 1, @rank := 1) rank,

b.diff-@rank flag from (

select

distinct

uid,

date_format(create_time,'%Y-%m-%d') create_time,

datediff(create_time,now()) diff

from test_sign_history order by uid,create_time

) b, (SELECT @gid := 1, @cgid := 1, @rank := 1) as a

) c group by uid,flag

order by uid,count(*) desc

) d,(SELECT @ggid := 1, @cggid := 1, @grank := 1) as e

)f

where grank=1;